THE STRUCTURE & MEANING OF THE MASS
The Mass begins with the entrance song. The celebrant and other ministers enter in procession and reverence the altar with a bow and/or a kiss. The altar is a symbol of Christ at the heart of the assembly and so deserves this special reverence.
All make the Sign of the Cross and the celebrant extends a greeting to the gathered people in words taken from Scripture.
The Act of Penitence follows the greeting. At the very beginning of the Mass, the faithful recall their sins and place their trust in God's abiding mercy. The Act of Penitence includes the Kyrie Eleison, a Greek phrase meaning, "Lord, have mercy." This litany recalls God's merciful actions throughout history. On Sundays, especially in the Season of Easter, in place of the customary Act of Penitence, from time to time the blessing and sprinkling of water to recall Baptism may take place.
On Sundays and solemnities, the Gloria follows the Act of Penitence. The Gloria begins by echoing the song of the angels at the birth of Christ: "Glory to God in the highest!" In this ancient hymn, the gathered assembly joins the heavenly choirs in offering praise and adoration to the Father and Jesus through the Holy Spirit.
The Introductory Rites conclude with the Opening Prayer, also called the Collect. The celebrant invites the gathered assembly to pray and, after a brief silence, proclaims the prayer of the day. The Opening Prayer gives a context for the celebration.
LITURGY OF THE WORD
Most of the Liturgy of the Word is made up of readings from Scripture. On Sundays and solemnities, there are three Scripture readings. During most of the year, the first reading is from the Old Testament and the second reading is from one of the New Testament letters. During the Easter season, the first reading is taken from the Acts of the Apostles which tells the story of the Church in its earliest days. The last reading is always taken from one of the four Gospels.
In the Liturgy of the Word, the Church feeds the people of God from the table of his Word (cf. Constitution on the Sacred Liturgy, no. 51). The Scriptures are the word of God, written under the inspiration of the Holy Spirit. In the Scriptures, God speaks to us, leading us along the path to salvation.
The Responsorial Psalm is sung between the readings. The psalm helps us to meditate on the word of God.
The high point of the Liturgy of the Word is the reading of the Gospel. Because the Gospels tell of the life, ministry, and preaching of Christ, it receives several special signs of honor and reverence. The gathered assembly stands to hear the Gospel and it is introduced by an acclamation of praise. During most of the year, that acclamation is "Alleluia!" derived from a Hebrew phrase meaning "Praise the Lord!" A deacon (or, if no deacon is present, a priest) reads the Gospel.
After the Scripture readings, the celebrant preaches the homily. In the homily, the preacher focuses on the Scripture texts or some other texts from the liturgy, drawing from them lessons that may help us to live better lives, more faithful to Christ's call to grow in holiness.
In many Masses, the Nicene Creed follows the homily. The Nicene Creed is a statement of faith dating from the fourth century. In certain instances, the Nicene Creed may be replaced by the Apostles' Creed (the ancient baptismal creed of the Church in Rome) or by a renewal of baptismal promises, based on the Apostles' Creed.
The Liturgy of the Word concludes with the Prayer of the Faithful or the General Intercessions. The gathered assembly intercedes with God on behalf of the Church, the world, and themselves, entrusting their needs to the faithful and loving God.
LITURGY OF THE EUCHARIST
The Liturgy of the Eucharist begins with the preparation of the gifts and the altar. As the ministers prepare the altar, representatives of the people bring forward the bread and wine that will become the Body and Blood of Christ. The celebrant blesses and praises God for these gifts and places them on the altar. In addition to the bread and wine, monetary gifts for the support of the Church and the care of the poor may be brought forward.
After the gifts and altar are prepared, the Eucharistic Prayer begins. This prayer of thanksgiving is the heart of the Liturgy of the Eucharist. In this prayer, the celebrant acts in the person of Christ as head of his body, the Church. He gathers not only the bread and the wine, but the substance of our lives and joins them to Christ's perfect sacrifice, offering them to the Father.
After a brief introductory dialogue, the celebrant begins the Preface. The Preface tells of the wonderful actions of God, both throughout history and in our lives, giving thanks to God for all these things. The Preface concludes with the Sanctus in which the whole assembly joins the song of the angels giving praise to the Father in heaven (cf. Is 6:3).
The next major part of the Eucharistic Prayer is the epiclesis. In the epiclesis, the priest asks the Father to send the Holy Spirit on the gifts of bread and wine so that, through the power of the Spirit, they may become the Body and Blood of Christ. This same Spirit will transform those attending the liturgy that they may grow in their unity with each other, with the whole Church, and with Christ.
The prayer continues with the institution narrative and consecration. This part of the prayer recalls the action of Jesus Christ on the night before his death. He gathered with his closest disciples to share a final meal. In the course of this meal, he took the simple bread and wine, blessed them, and gave them to his friends as his Body and Blood. In our Eucharistic celebration, through the words of the priest and the action of the Holy Spirit, simple bread and wine once again become the Body and Blood of Christ.
The Eucharistic Prayer continues with the anamnesis, literally, the "not forgetting." The people proclaim the memorial acclamation, recalling the saving death and resurrection of the Lord. The prayer continues as the celebrant recalls the saving actions of God in Christ.
The next part of the prayer is the offering. In this part of the prayer, the priest joins the offering of this Mass to the perfect sacrifice that Jesus made on the cross. The priest offers this sacrifice back to God the Father in thanksgiving for God's abundant gifts, particularly the gift of salvation in Christ. The priest also prays that the Holy Spirit may come upon the faithful and by receiving the body and blood of Christ, they themselves may become a living offering to God.
The intercessions follow. Confident in God's loving care, the gathered assembly makes this sacrifice on behalf of the living and the dead, for the leaders of the Church and for all the faithful.
The Eucharistic Prayer concludes with the Final Doxology. The celebrant makes the prayer through, in, and with Jesus, in union with the Holy Spirit, and presents it to God the Father. The people respond with the Great Amen a joyous affirmation of their faith and participation in this great sacrifice of praise.
The Communion Rite follows the Eucharistic Prayer, leading the faithful to the Eucharistic table.
The rite begins with the Lord's Prayer. Jesus taught this prayer to his disciples when they asked how to pray (cf. Mt 6:9-13, Lk 11:2-4). In this prayer, the people join their voices to pray for the coming of God's kingdom and to ask God to provide for our needs, forgive our sins, and bring us to the joy of heaven.
The Rite of Peace follows. The celebrant prays that the peace of Christ will fill our hearts, our families, our Church, our communities, and our world. As a sign of hope, the people extend to those around them a sign of peace, typically by shaking hands.
In the Fraction Rite, the celebrant breaks the consecrated bread as the people sing the Agnus Dei or "Lamb of God." John the Baptist proclaimed Jesus as "the Lamb of God who takes away the sin of the world" (Jn 1:29). The action of breaking the bread recalls the actions of Jesus at the Last Supper, when he broke the bread before giving it to his disciples. One of the earliest names for the Eucharistic celebration is the breaking of the bread.
Before receiving Communion, the celebrant and assembly acknowledge that we are unworthy to receive so great a gift. The celebrant receives Communion first and then the people come forward.
Those who receive Communion should be prepared to receive so great a gift. They should fast (except for medicines) for one hour before receiving the Eucharist and should not be conscious of having committed serious sin.
Because sharing at the Eucharistic Table is a sign of unity in the Body of Christ, only Catholics may receive Communion. To invite all present to receive Communion implies a unity which does not exist.
Those who do not receive Communion still participate in this rite by praying for unity with Christ and with each other.
The people approach the altar and, bowing with reverence, receive Communion. People may receive the Body of Christ either on the tongue or in the hand. The priest or other minister offers the Eucharist to each person saying, "The Body of Christ. The person receiving responds by saying, "Amen," a Hebrew word meaning, "So be it" ( Catechism of the Catholic Church, 2856).
As the people receive Communion, the communion song is sung. The unity of voices echoes the unity the Eucharist brings. All may spend some time in silent prayer of thanksgiving as well.
The Communion Rite ends with the Prayer after Communion which asks that the benefits of the Eucharist will remain active in our daily lives.
When it is necessary, announcements may be made. The celebrant then blesses the people assembled. Sometimes, the blessing is very simple. On special days, the blessing may be more extensive. In every case, the blessing always concludes "in the name of the Father, and of the Son, and of the Holy Spirit." It is in the triune God and in the sign of the cross that we find our blessing.
After the blessing, the deacon dismisses the people. In fact, the dismissal gives the liturgy its name. The word "Mass" comes from the Latin word, " Missa." At one time, the people were dismissed with the words " Ite, missa est," meaning "Go, you are sent. The word " Missa" comes from the word " missio," the root of the English word "mission." The liturgy does not simply come to an end. Those assembled are sent forth to bring the fruits of the Eucharist to the world.